The potent androgens dimethandrolone 17-undecanoate (DMAU) and 11-methyl-19-nortestosterone 17-dodecylcarbonate (11-MNTDC) are in development for androgen replacement therapy and hormonal contraception in men. They can be delivered either orally or as long-acting injectables. In the current study, their long-term effects on body composition (percentage lean and fat mass), bone mineral density (BMD), serum gonadotropin levels, and the weights of the prostate, seminal vesicles, and levator ani muscle were assessed. Four-week old male rats were sham-operated (Intact) or castrated (Cx) and treated sc for 16 weeks post-surgery with vehicle (Cx, Intact), DMAU or 11-MNTDC every 4 weeks, testosterone enanthate (TE) every 2 weeks, or a testosterone (T) implant. There were significant differences in body weights over time with a general trend of Intact = Cx+T = Cx+TE >Cx+11-MNTDC >Cx >Cx+DMAU. At week 18, rats were evaluated by dual energy x-ray absorptiometry (DEXA) using the whole body function of the Hologic software. The percentage lean body mass and BMD were lower (P<0.05) in Cx rats than Intact rats, but equivalent in all groups of androgen-treated Cx rats and Intact rats (P>0.05). The highest percentage body fat was observed in Cx rats. Only DMAU- and 11-MNTDC-treated rats had lower percentage body fat compared to Cx rats (P<0.05). Prostate, seminal vesicles, and levator ani muscle weights, corrected for final body weight, were decreased (P<0.05) in Cx compared to Intact rats and increased to varying extents in androgen-treated Cx rats compared to Cx rats (P<0.05). Most marked increases were observed in the DMAU-treated rats in which prostate and seminal vesicle weights/kg body weight were 2.4 to 2.7 times those of Intact rats, and levator ani muscle weights were increased about 1.5-fold. Blood was collected from the tail vein at weeks 4, 8, 12, and 16 for measurement of serum levels of androgens and at necropsy on week 18 for measurement of serum gonadotropins. Serum LH and FSH were greatly elevated in Cx rats at week 18 and suppressed to levels in comparable to those in Intact rats by DMAU, 11-MNTDC, and T implants (P>0.05) but not by TE (P<0.05). Collectively, our data indicate that androgen replacement with DMAU or 11-MNTDC in Cx rats resulted in favorable changes in body composition and maintenance of BMD comparable to those of T.